N-heterocyclic carbene complexes of palladium in oxygen atom transfer reactions involving the making and breaking of N-O bonds

Xiaochen Cai, Subhojit Majumdar, Leonardo F. Serafim, Manuel Temprado, Steven P. Nolan, Catherine S.J. Cazin, Burjor Captain, Carl D. Hoff

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Reaction of three equivalents of MesCNO (Mes = 2,4,6-trimethylphenyl) with one equivalent of [Pd(IPr)(P(p-tolyl)3)] in toluene yields the solid complex [Pd(IPr)(NCMes)(κ2-O–N[dbnd]C-Mes(–N–C([dbnd]O)Mes))]. Three major steps are proposed to be involved in the reaction based on spectroscopic studies as well as literature precedents for related cycloadditions: i. oxidation of the coordinated phosphine ligand to phosphine oxide ii. oxygen atom transfer forming a C[dbnd]O bond from the N–O bond of MesCNO, and iii. cycloaddition of a final MesCNO ligand to yield product. Addition of two equivalents of [rad]NO at low temperature to the in situ generated peroxide complex [Pd(IPr)22-O2)] generates the N-bonded complex trans-[Pd(IPr)2(NO2)2] in keeping with a literature precedent reported for similar complexes. Insight into the energetics of this reaction are probed by DFT calculations using the truncated ligand complex [Pd(IMe)2]. The computed enthalpy of binding of two moles of [rad]NO2 to form [Pd(IMe)2(NO2)2] is −112 kcal/mol indicating that its preparation from [Pd(IMe)2], N2 and 2O2 is thermodynamically favorable by −96 kcal/mol. Crystal structures of [Pd(IPr)(NCMes)(κ2-O–N[dbnd]C-Mes(–N–C([dbnd]O)Mes))] and trans-[Pd(IPr)2(NO2)2] are reported.

Original languageEnglish (US)
Pages (from-to)285-293
Number of pages9
JournalInorganica Chimica Acta
Volume468
DOIs
StatePublished - Nov 1 2017

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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